If you have ever spent more than ten minutes inside a Bitcoin chat room, you have probably heard the name Plan B tossed around like gospel. The anonymous Dutch analyst's stock-to-flow model once turned a niche quantitative exercise into the most-watched price forecast in crypto. But after several years of bitter misses and brutal corrections, believers and skeptics are once again squaring off. Is Plan B's Bitcoin model still a useful lens, or has it gone the way of every other busted prophecy?

Who Is Plan B and What Is the Stock-to-Flow Model?

Plan B is the pseudonym of a European quant who, in early 2019, published a Medium article arguing that Bitcoin's scarcity, measured against its existing supply, could predict its market value. The idea itself is not new. Stock-to-flow (S2F) is a ratio used in commodities like gold and silver, comparing the total existing stockpile to the amount produced each year. Gold's S2F sits above 60, silver near 30, and Bitcoin, by design, climbs higher with every halving.

The original model treated Bitcoin as digital gold and plotted its S2F value against price on a log scale. The fit was almost suspiciously clean through the 2009–2019 data. Plan B doubled down in 2020 with a cross-asset update that placed Bitcoin, gold, and silver on the same curve, suggesting a price target north of $100,000 by the end of 2021.

The math, in plain English

Every four years, Bitcoin's new issuance is cut in half. That predictable supply shock, combined with steady or rising demand, is the engine of the model. After the third halving in 2020, the S2F ratio jumped to roughly 56, putting Bitcoin closer to gold than ever before. Plan B argued this scarcity alone justified a six-figure price tag.

Why the S2F Model Captivated Bitcoiners

Bitcoiners are not used to getting numbers. Most forecasts in crypto come from influencers waving hand-drawn lines on weekly charts. Plan B offered something different: a defensible mathematical relationship grounded in scarcity economics. Suddenly, Bitcoin had a model that looked, at a glance, almost as tidy as a physics equation.

  • It framed Bitcoin as a monetary asset, not just a speculative token, anchoring it to the same scarcity story that powers gold.
  • It gave holders a thesis: rising scarcity, rising price, full stop.
  • It produced round-number targets that were easy to remember, easy to share, and easy to bet on.

The first half of 2021 looked like vindication. Bitcoin blasted through $60,000 and flirted with $69,000 in November, leaving many to assume the mythical $100,000 was days away. Plan B's Twitter feed became required reading.

Where the Model Has Stumbled

Then came 2022, and the narrative cracked. Bitcoin's price collapsed by more than 70 percent from its peak, yet the S2F line stubbornly implied a valuation multiples higher than reality. Plan B defended the framework by pointing to a planned S2FX upgrade, a multi-asset version that introduced phase transitions and a fourth dimension. Critics, however, argued that any model you have to keep patching to fit the data is no longer a model, it is a story.

Statistical blowback followed. Researchers at the University of Copenhagen and elsewhere published papers pointing out that the original 2019 fit relied on cherry-picked dates, that the residuals were not normally distributed, and that an over-reliance on log-log plots tends to inflate correlations. In plain terms, the famous tight line looked tight because of how the axes were drawn, not because the underlying relationship was ironclad.

The 2024 halving test

April 2024 brought the fourth Bitcoin halving, slicing the block reward from 6.25 to 3.125 BTC and pushing the S2F ratio above 120, more than double gold's. Pure model logic said price should follow. So far, the post-halving year has been choppy, defined more by ETF flows and macro liquidity than by any clean scarcity-driven trajectory. Plan B has continued publishing revised versions, but each tweak has chipped away at the simplicity that made the original so appealing.

Can Plan B's Framework Still Guide Investors?

Throwing out the entire framework is just as lazy as worshipping it. The stock-to-flow intuition still holds a kernel of truth: scarcity, in the long run, is the most defensible property of Bitcoin, and no government can vote it into existence. That is worth more than a price target.

What smart investors should keep from Plan B is the discipline of thinking in halving cycles, watching issuance, and treating Bitcoin as a hard-money asset. What they should discard is the assumption that any single model, however elegant, can pin a price on a market that also responds to interest rates, ETF inflows, regulation, and global liquidity. Use S2F as one input, not a crystal ball.

Key Takeaways

  • Plan B's stock-to-flow model made Bitcoin scarcity a quantifiable thesis and briefly turned scarcity math into the most-cited forecast in crypto.
  • The framework has repeatedly missed its price targets, especially through the 2022 bear market and the 2024 halving year, prompting credible academic criticism.
  • The core idea, that Bitcoin's fixed supply is its biggest edge, remains intact, but no single model should be treated as a guaranteed roadmap.
  • Use S2F as a long-term compass, not a short-term trading signal, and always pair it with macro context.